Organic geochemistry of tithonian source rocks and associated oils from the Sonda de Campeche, Mexico

Santamaria Orozco, D. M.

Book/Report

FZJ-2014-03034

Organic geochemistry of tithonian source rocks and associated oils from the Sonda de Campeche, Mexico

Santamaria Orozco, D. M. (Corresponding author)FZJ*

2000
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Berichte des Forschungszentrums Jülich 3763, 201 pp. (2000)

Please use a persistent id in citations: http://hdl.handle.net/2128/6741

Report No.: Juel-3763

Abstract: The Sureste Basin is the most prolific petroleum zone in Mexico and one of the mostimportant of the world . This includes offshore portion of Campeche and Tabasco states andthe onshore part of Campeche, Chiapas and Tabasco states . The discovery in 70's of the largeoil fields of the Sonda de Campeche gave impulse to the development of geophysical,geocherrücal and geological projects in this region of the country . Although it has been knownfor many years that the main source rock was the Tithonian, details of its compositionalvariability are scarce . This study evaluates the source potential of the Tithonian rocks in theSonda de Campeche through the use of additional methods and more abundant data. Theevaluation was performed through the physical and chemieal characterisation of the sourcerock using organic geochemistry, organic petrology and petrophisics within sedimentologicalframework. In this study 86-rock samples from 28 cores in 13 wells and 19 crude oils from 14wells, were analysed . Well logs from 12 wells were also used.Screening analysis confirm that the Tithonian rocks have the highest total organic carbon(TOC) of the studied geological Mulm (with average of 2 .8 % wt TOC), and that otherKirnrneridgian and Oxfordian rocks also have high TOC values (with average of 1 .5 % wtTOC), but only in very restricted areas. Therefore the Tithonian rocks are consideredpetroleum source rocks. The organic matter (OM) is uniforrnly composed of kerogen types 1 -11. The Tithonian sequence was deposited in a carbonate platform environment under anoxicconditions during a marine transgression . The organic matter is rieh in liptinites, mainlycomposed of algal and amorphous organic material, and can be divided into three subfaciesusing organic petrology . The first in the northeast (BI), the second in the central part (B2) andthe third in the southwest (B3) . Petrographie data (i .e. lithologic composition consisting ofcarbonates, siliciclastics and micro-dolomites with lanfinalions and absence or scarcebioturbation, presence of amorphous OM, algae, chlorophyllinite, calciaesferulids, radiolaria,fish bones and ammonites) as well as geochemical data (i .e . an average of 50% CaCO3ranging from 3 .33 to 96 .75%) confi nn this interpretation.Maturity varies from irnmature in the NE to overmature in the SW, from 0 .35 to 1 .29 percentof the vitrinite reflectance (% R 0) and liptinites colour from light yellow to brown orange . Themaximum Rock-Eval pyrolysis temperature (Tmax) also shows this variation, from 405 in theNE to 467 °C in the SW . The extracts also show bulk compositional variation in accordancewith the classical o window concept .

Contributing Institute(s):